This photo taken on January 31, 2017 shows US Senator Orrin Hatch, R-Utah, attending a meeting on Capitol Hill in Washington, DC. (By AFP)

The longest-serving Republican member of the US Senate, Orrin Hatch, has announced that he will retire at the end of his term in November this year.

The 83-year-old senator from the US state of Utah made the announcement in a video posted to twitter on Tuesday, saying, he was “deeply grateful” to serve as a senator and that a new chapter in his life was just beginning.

“I’ve always been a fighter. I was an amateur boxer in my youth, and I brought that fighting spirit with me to Washington. But every good fighter knows when to hang up the gloves,” Hatch said.

“And for me, that time is soon approaching. That’s why, after much prayer and discussion with family and friends, I’ve decided to retire at the end of this term,” he added.

This photo taken on December 4, 2017 shows US President Donald Trump alongside US Senator Orrin Hatch (L), Republican of Utah, as they disembark from Air Force One upon arrival at Salt Lake City International Airport in Utah. (By AFP)

Hatch’s decision to leave the Senate after more than 40 years comes despite US President Donald Trump’s public encouragement for him to run for re-election.

The Republican played a significant role as chairman of the Senate Finance Committee in crafting the overhaul of the US tax code, which was passed last month.

White House Press Secretary Sarah Huckabee Sanders said Trump was “very sad” to see the most senior Republican in the US Senate leave and is thankful for his “massive effort” toward passing the tax legislation.

“The president, certainly, has the greatest and deepest amount of respect for Senator Hatch and his over four decades of experience in the Senate,” Sanders told reporters in the White House. “The president certainly praises his service and is very sad to see Senator Hatch leave.”

The Tuesday announcement could clear the path for Mitt Romney, former Republican presidential candidate and one of the party’s most vocal critics of Trump, to replace him in the Senate.

Romney, who lives in Utah and is popular in the state, thanked Hatch in a statement later in the day, but did not address whether he plans to enter the race and run for the seat in this year’s midterm elections.

“Senator Hatch has represented the interests of Utah with distinction and honor,” he said in a post on Facebook.

Romney engaged in a verbal clash with Trump during the 2016 election, calling the New York billionaire businessman a “phony” and a “fraud.” And more recently, Romney censured failed Alabama Senate candidate Roy Moore after the US president endorsed him amid sexual misconduct allegations.